Run this action in 16 bits and in ProPhoto RGB and sRGB, theaction will separate color and luminosity and will recombinethe result, then the result is compared to the original to seeif anything has changed...

The original image does not need to be in ProPhoto RGB or 16 bitsand you do not need a wide gamut monitor.

Using this photo as an example, look what will happen to her dresswhen the Color Space is not ProPhoto RGB.